This invention relates to the hot melt sizing of textile warp yarns, more specifically to a novel class of non-aqueous warp sizes which are applied to yarn in the form of a melt.
For some years it has been recognized that a system for melt sizing of warp yarns would offer many advantages. At the sizing symposium of Sept. 9-12, 1974 in Budapest, Hungary (Melliand Textilberichte, English Edition, April, 1975, p. 262), it was observed, with respect to sizing machines and sizes: "All problems related with drying (energy costs, error sources) can be avoided, if sizing agents can be used which rigidify at room temperature. At present there is no satisfactory and practical solution; but it is probable that melt sizes will be important in the future." Both before and since that time ongoing research on melt sizes and melt sizing methods and apparatus has led to the development and patenting of a number of new size compositions. Various deficiencies, principally economic in nature, have nevertheless limited the commercial acceptability of these sizes.
U.S. Pat. No. 3,466,717 describes a method and apparatus for sizing warp yarns, in which size is applied within a sizing chamber provided with a vat containing a quick-solidifying molten size whose predominant component is wax. Exemplified for application in this apparatus is a molten size made with hardened castor oil, 2-ethylhexyl acrylate, and benzoyl peroxide, one of a number of sizes described in Japanese Patent Publication No. 14280/1965 (issued Dec. 22, 1965, as Japanese Pat. No. 462,254). More broadly, the latter publication describes certain classes of polymers or copolymers soluble in specified types of wax, capable of application to yarns by melt means. Three facts in this publication are particularly significant in the context of the present invention. The first is its emphasis upon high compatibility of its various simple or mixed polymer components with its wax components. The second is that at least 20 percent of a hydrophobic vinyl monomer, such as 2-ethylhexyl acrylate, must be present in its polymeric component if compatibility with the wax is to be achieved. The third is that a substantial portion of an ester of a hydroxycarboxylic acid, such as found in hydrogenated castor oil or esters of hydroxyacids such as tartaric acid, must be present. A minimum of 40 percent of this special kind of hydroxy ester wax is required as a component in the size compositions described in the Japanese patent publication.
Corollary to these facts is the publication's insistence on a 60 percent maximum of hydrogenated tallow in the wax component itself, which latter serves as solvent for the polymeric component. More specifically, the document's examples show no size composition containing in excess of 24 percent of hydrogenated tallow. The Japanese patent publication clearly does not contemplate the use of high proportions, i.e., in the order of 50 percent, of readily available hydrogenated tallow in a melt size composition.
U.S. Pat. No. 4,136,069 describes melt sizes made from a polymeric blend of high molecular weight with low molecular weight ethylene/.alpha.,.beta.-unsaturated carboxylic acid copolymers, such, for example, as blends of high with low molecular weight ethylene/acrylic acid copolymers. These melt blends are employed as sizes either alone or in conjunction with 0-50 percent of one or more C.sub.5 -C.sub.12 dicarboxylic acids and/or with 0-30 percent, preferably 5-20 percent, of wax, fatty acid, or monoglyceride. With regard to the wax component, the patent makes no mention of animal or vegetable wax. Fischer-Tropsch or predominantly hydrocarbon waxes, the only classes of wax identified by name, are represented as only a minor substituent in a single example, at a level of 2.5 percent, in conjunction with 17.5 percent of a monoglyceride.
It is therefore an object of the present invention to provide a melt size containing substantially more hydrogenated tallow or equivalent triglyceride wax than hitherto tolerable in textile melt sizes.
It is a further object of the present invention to provide a melt size that is removable from fabric by either aqueous or organic solvent extraction or scouring means.
It is a further object of the present invention to provide a melt size exhibiting minimal smoking and fuming during hot melt size application to yarn.
It is a further object of this invention to provide a melt size giving superior weaving through the enhanced abrasion resistance and fiber laydown of staple yarns to which it has been applied.
These and other objects will be apparent from the following detailed description of our invention.